A touch panel is an input device used to identify a particular sub-region of an overall touch sensitive area implemented by the touch panel when that sub-region is touched by a user of a device incorporating the touch panel. Touch panels are typically affixed as an overlay to information presentation screens such as light-emitting diode (LED) screens, liquid crystal display (LCD) screens, cathode-ray tube (CRT) screens, etc. to create a monolithic touch sensitive display input/output device.
Touch panels may be designed to detect a human touch using various technologies. A typical capacitive touch panel may have a series of thin conductive patterns fabricated on a clear substrate with a clear insulating layer covering the conductive pattern layer. Each of the series of thin conductive patterns forms one plate of a capacitor and the clear insulating layer forms the capacitor insulator. A human finger in contact with the clear insulating layer is also a conductor, and distorts the electrostatic fields surrounding one or more of the energized conductive patterns around the touched area. The field distortions are read out as changes in capacitance.
A grid of row and column energizing and sensing conductors commonly form an X-Y pattern of row/column crossover points referred to herein as X-Y nodes. In a typical touch panel implementation, for example, a capacitive touch panel may energize a single row of the conductive patterns while measuring a magnitude of capacitance associated with each column, one column at a time. The touch panel may then energize a next row of conductive patterns while measuring the capacitance of each column in turn, until a complete touch panel scan has collected a capacitance value for each X-Y node on the panel.